The present invention relates to the laser sensor art.
Heretofore, laser sensors have included a laser diode or other laser source which was focused to a preselected focal length by a convergent focusing lens. Laser light reflected from a reflector was received by another convergent lens with a relatively long focal length and focused on a photodiode detector. The output of the photodiode was monitored and an electronic signal was generated indicative of the reception of the reflected laser beam or the absence of the reflected laser beam. In order to distinguish between the reflected laser beam and stray light of like color, some laser sensors included a feedback system, such as a continuous wave type feedback system, between the laser source and the detector.
Although successful, such prior laser sensors have drawbacks. First, the prior laser sensors are typically operative for a relatively short distance range, on the order of up to 30 meters. Even within that distance range, different lenses on the laser are required for different distances. Typically, the selected laser sensor must be matched to the application. Although less critical on the receiving side, the receiving lenses again must be compatible with the distance for which the sensor is calibrated. The longer focal length lenses at the receiving side tend to use only part of the photodetector as the length becomes longer, reducing sensitivity. If the length is too long, the lens may focus off the photodetector.
The present invention provides a new and improved laser sensor which overcomes the above-referenced problems and others.